Cable Television (CATV) Networks have been undergoing rapid upgrading, particularly in North America, to provide advanced services, such as digital video, telephony and Internet services. A major part of the upgrade cycle has been the development of the return path network—the path from residential subscribers to the CATV Headend. Previously, this portion of the network was used very little, and only for minor maintenance and billing operations. As interactivity needs grew and CATV technology advanced, this portion of the network became more significant. Now, the CATV return path forms a critical portion of the system for two-way interactivity, such as telephony and data traffic.
One key issued in determining the performance of the CATV return path is the quality of the return cable channel. Within this path, one of the most significant impairments to quality signal transmission arises from external interference, typically caused by narrowband interference of radio waves or in-home sources that generate narrowband frequency domain noise that falls within the return band of 5-42 Megahertz (MHz) (North America). Additionally, it is commonly the case that return path networks, when terminated at a CATV Headend, are combined with other return path networks. Thus, interference from one return leg of one network not only degrades or ruins the channel within which such interference falls, but also ruins channels on other legs that otherwise are clean until they reach the combining point at the CATV Headend.
In many two-way HFC communication networks, return path systems are limited in performance by interference generated from multiple reverse path sources in the plant and in homes. Additionally, the return path is band limited, so the spectrum obscured by interference is very valuable.
Today, field personnel perform extensive testing and troubleshooting throughout the network to identify potential narrowband interference sources. This is a costly and ongoing, time-consuming process. Moreover, many of the problems exist inside homes and therefore cannot be addressed by such troubleshooting.
The present invention is therefore directed to the problem of developing a method and apparatus for improving the performance of return paths in two-way HFC communication networks.